X[docker]: add python3-pexpect support

Signed-off-by: nietingting <nietingting@xiaomi.com>
diff --git a/cibuild.sh b/cibuild.sh
index 3178cb3..5b627b1 100755
--- a/cibuild.sh
+++ b/cibuild.sh
@@ -58,6 +58,7 @@
   PYTHONUSERBASE=$prebuilt/pylocal
   export PYTHONUSERBASE
   add_path $PYTHONUSERBASE/bin
+  pip3 install pexpect
 }
 
 function u-boot-tools {
diff --git a/docker/linux/Dockerfile b/docker/linux/Dockerfile
index 3a0d7a2..58797a4 100644
--- a/docker/linux/Dockerfile
+++ b/docker/linux/Dockerfile
@@ -113,6 +113,7 @@
   python-is-python3 \
   python3-pip \
   python3-setuptools \
+  python3-pexpect \
   make \
   cmake \
   ninja-build \